For a long time they wore 5 fingers - usually they buy 40-41 depending on the shoe. Based on the reviews I ordered 42 and it was perfect. A bit big but perfect for extra socks, but the regular weight Injinji fleece was about as warm as I needed for freezer work. I didn't really understand how it could be good for ice but bad for snow, but the first time I put it on I got it. When you step on snow or a puddle, water seeps in between your toes or through your shoes, which are essentially thick warm blankets that aren't waterproof. But for walking on ice or concrete, or standing in the freezer for long periods of time, it's great.